JP2022138348A - Servo driver and servo system - Google Patents

Abstract

To increase the accuracy of detection of servomotor replacement.SOLUTION: A servo driver for controlling a servomotor including an encoder and a motor body comprises: a servo control unit for controlling the servomotor by servo control; a calculation unit for acquiring data of a nonvolatile memory, which is arranged in the encoder and can be accessed by the servo driver when the servo driver is electrified, as a chunk of prescribed data, and for performing an arithmetic processing of the calculation of a hash value by inputting the acquired prescribed data into a hash function; a memory unit for memorizing the hash value calculated by the calculation unit; and a detection unit for detecting the replacement of the servomotor, when the prescribed hash value, which is acquired by the arithmetic processing by the calculation unit to the nonvolatile memory of the prescribed encoder, the memory being able to be accessed by the servo driver when the servo driver is electrified next, is different from the hash value memorized in the memory unit.SELECTED DRAWING: Figure 4

Description

The present invention relates to servo drivers and servo systems.

In a servo system, servo control of a servo motor is generally performed by a servo driver according to commands from a controller such as a PLC. Each servo motor has its own parameters. The servo driver acquires such parameters from a non-volatile memory such as an electrically erasable programmable read-only memory (EEPROM) of an encoder provided in the servo motor, and performs servo control of the servo motor using the acquired parameters.

Since the parameters of the servomotor are different for each servomotor, when the servomotor is replaced, the parameters are reacquired from the replaced servomotor. Therefore, the servo driver performs individual recognition of the servo motor based on the identification information of the servo motor such as the serial number of the motor and the encoder stored in the non-volatile memory of the encoder, and if the identification information is different, the servo motor is replaced. detect that Then, when the servo driver detects replacement of the servo motor, it is possible to report an abnormality.

JP-A-8-023692 JP 2018-021789 A WO2014/109054

If the servo driver and the servo motor are supplied from different sources, it may be unclear in which area of the non-volatile memory of the encoder the identification information is stored. In such a case, since the servo driver cannot acquire the identification information from the servo motor, it cannot detect replacement of the servo motor. Therefore, the servo driver cannot issue an error report, and there is a risk that the parameters obtained from the pre-replacement servo motor will be used to perform servo control of the post-replacement servo motor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a servo driver and a servo system capable of improving detection accuracy of replacement of a servo motor.

One aspect of the disclosed technology is exemplified by the following servo driver. The present servo driver is a servo driver for controlling a servo motor including an encoder and a motor main body, comprising a servo control section for servo-controlling the servo motor and a memory provided in the encoder, a calculation unit that acquires data in a nonvolatile memory that can be accessed from the servo driver when the power is turned on as a block of predetermined data, inputs the acquired predetermined data into a hash function, and performs arithmetic processing to calculate a hash value; a storage unit for storing the hash value calculated by the calculation unit; a detection unit that detects replacement of the servo motor when a predetermined hash value obtained by performing the processing is different from the hash value stored in the storage unit.

The servo driver acquires data stored in the non-volatile memory of the encoder and detects replacement of the servo motor based on the hash value. That is, since the servo driver does not acquire and compare information such as serial numbers from the servo motors, it can detect the replacement of the servo motors even if the arrangement of the data stored in the non-volatile memory is unknown. be able to. Therefore, according to the above servo driver, it is possible to improve the detection accuracy of replacement of the servo motor. For example, the calculation unit may acquire all data stored in the nonvolatile memory of the encoder as predetermined data. The storage unit of the servo driver may store the hash value calculated by the calculation unit at the time when the servo driver is most recently energized.

Here, the calculation unit obtains, as the predetermined data, the data stored in the nonvolatile memory of the encoder, excluding variable data accessible by the servo driver and whose value fluctuates. can be Variable data whose values fluctuate, such as measurement data measured by various sensors such as temperature sensors, may be stored in the nonvolatile memory. By excluding such variable data, the servo driver is prevented from erroneously detecting that the servo motor has been replaced even though the servo motor has not been replaced.

In the arithmetic processing, the calculation unit may calculate hash values of the predetermined data for each of a first hash function of a first algorithm and a second hash function of a second algorithm. Then, the detection unit uses the hash value calculated by the first hash function stored in the storage unit and the first hash function in the arithmetic processing when the next servo driver is energized. The hash value is compared with the hash value calculated by the second hash function stored in the storage unit and the hash value obtained by using the second hash function in the arithmetic processing when the next servo driver is energized. is compared with the hash value, and if at least one of the hash value calculated by the first hash function and the hash value calculated by the second hash function is different, replacement of the servo motor is detected. may be In a hash function, collisions can occur in which the same value is calculated even though the input data are different. By using two different algorithms, it is possible to suppress the decrease in detection accuracy of motor replacement due to the occurrence of such collisions.

The servo control section prohibits control of the servo motor connected to the servo driver at that time when the detection section detects replacement of the servo motor while the servo driver is energized. may By providing such a feature, it is possible to suppress the control of the post-replacement servomotor with the parameters set for the control of the pre-replacement servomotor.

Here, the present invention can also be viewed from the aspect of the servo system. That is, this servo system includes a servo motor including an encoder and a motor body, and a servo driver that controls the servo motor. The servo driver includes a servo control unit for servo-controlling the servo motor, and a memory provided in the encoder. a calculation unit that performs arithmetic processing to calculate a hash value by inputting the obtained predetermined data into a hash function, a storage unit that stores the hash value calculated by the calculation unit, and When the servo driver is energized, the storage unit stores a predetermined hash value obtained by performing the arithmetic processing by the calculation unit on a nonvolatile memory of a predetermined encoder accessible from the servo driver. a detection unit that detects replacement of the servo motor when the hash value is different from the hash value.

According to the disclosed technology, it is possible to improve the detection accuracy of servo motor replacement.

FIG. 1 is a diagram schematically showing a configuration example of a servo system. FIG. 2 is a diagram showing a schematic configuration of the motor. FIG. 3 is a first diagram showing an example of data stored in a storage unit of an encoder; FIG. 4 is a diagram showing a schematic configuration of functional units of the servo driver. FIG. 5 is a diagram showing a processing flow for detecting replacement of a motor by a servo driver. FIG. 6 is a second diagram showing an example of data stored in the storage unit of the encoder. FIG. 7 is a diagram showing a detection flow for detecting replacement of the motor by the servo driver in the first modified example. FIG. 8 is a diagram showing a detection flow for detecting replacement of the motor by the servo driver in the second modification.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. This disclosure presents an industrial system as one exemplary form of servo system. However, the application of the servo system according to the present invention is not particularly limited.

<Embodiment>
FIG. 1 is a diagram schematically showing a configuration example of a servo system 100. As shown in FIG. Servo system 100 includes a Programmable Logic Controller (PLC) 1 and a servo driver 2 . A servo driver 2 is arranged to drive and control the servo motor 3 . An output shaft 32 of the servomotor 3 is connected to a screw shaft 52 by a coupling 51 . A precision stage 53 is arranged on the screw shaft 52 , and is configured to be displaced by driving a servomotor (hereinafter referred to as “motor”) 3 . Stoppers (not shown) are provided at both ends of the driving range of the precision stage 53 along the screw shaft 52 . The impact when the precision stage 53 contacts the stopper is reduced as much as possible by controlling the torque of the motor 3 . A work 8 is placed on the precision stage 53 . As described above, in the illustrated servo system 100, one drive shaft is provided for the motor 3, but two or more drive shafts may be provided.

Here, the PLC 1 outputs command signals to the servo driver 2 . The PLC 1 functions, for example, as a monitoring device for the servo driver 2 by executing processing according to a program prepared in advance.

Then, the servo driver 2 receives a command signal from the PLC1. Further, servo driver 2 receives a feedback signal from motor 3 . In the servo driver 2, a servo system that performs feedback control using a position controller, a speed controller, a current controller, etc. is formed, and these signals are used to servo-control and drive the motor 3. do.

Also, the motor 3 includes a motor body 30 and an encoder 31 . The motor 3 is, for example, an AC servomotor. The motor 3 is supplied with drive current from the servo driver 2 through a power line 40 . The encoder 31 detects displacement of the output shaft 32 of the motor body 30 . Examples of the displacement of the output shaft 32 detected by the encoder 31 include the direction of rotation, the amount of rotation, and the speed of rotation of the output shaft 32 . The encoder 31 outputs a feedback signal indicating the detected displacement to the servo driver 2 via the encoder cable 41 .

Next, the functional configuration of the encoder 31 will be explained. FIG. 2 is a diagram showing a schematic configuration of the motor 3. As shown in FIG. The encoder 31 included in the motor 3 includes a signal generation section 311 , a communication section 312 and a storage section 313 .

The signal generator 311 detects the motion of the motor body 30 of the motor 3 driven by the servo driver 2 and generates a feedback signal indicating the detected motion. The feedback signal is output to communication section 312 . The feedback signal includes, for example, information about the rotational position (angle) of the rotating shaft of the motor body 30, information about the rotating speed of the rotating shaft, information about the rotating direction of the rotating shaft, and the like. For example, a known incremental type or absolute type configuration can be applied to the configuration of the signal generator 311 .

A communication unit 312 is an interface for communicating with the servo driver 2 . In this embodiment, the communication unit 312 sends feedback signals to the servo driver 2 via the encoder cable 41 . In this embodiment, serial communication is applied to the transmission of the feedback signal and detection signal from the communication section 312 . As a result, the number of signal lines included in the cable can be reduced. A known communication standard such as Recommended Standards 232 (RS-232C), RS-422, or RS-485 can be adopted for serial communication by the encoder cable 41 .

The storage unit 313 is a storage unit that stores data related to servo control of the motor 3 . The storage unit 313 is, for example, an EEPROM. FIG. 3 is a first diagram showing an example of data stored in the storage unit 313 of the encoder 31. As shown in FIG. In FIG. 3, the position where data is stored and the data stored in that position are shown in association with each other. The location is indicated, for example, by an address. The storage unit 313 stores data related to the encoder 31 such as the encoder serial number and various parameters. The manufacturer that manufactures the encoder 31 and the manufacturer that manufactures the motor body 30 may be different. Therefore, the storage unit 313 is further provided with a motor area. In FIG. 3, arrows indicate the data stored in the motor area.

Various parameters used for driving the motor body 30 are stored in the motor area by the manufacturer of the motor body 30 . In the example of FIG. 3, the motor area stores the motor model name, motor serial number, and servo control parameters. The parameters for servo control of the motor body 30 are adjusted for each individual motor body 30 . Therefore, the parameters for servo control of the motor bodies 30 may differ for each individual motor body 30 (for each serial number of the motor body 30) even if the motor bodies 30 have the same model name. That is, even if the model name of the motor body 30 is the same, servo control parameters suitable for servo control may differ for each individual motor body 30 .

The storage unit 313 stores preset data as described above. The data stored in the storage unit 313 is transmitted from the communication unit 312 to the servo driver 2 in accordance with commands from the servo driver 2 . Note that the configuration of the storage unit 313 shown in FIG. 3 is merely an example, and the configuration of the storage unit 313 is determined by the manufacturer of the encoder 31 and differs depending on the encoder 31 .

When the supplier of the servo driver 2 and the motor 3 is the same, the supplier can set the configuration of the storage unit 313 to the servo driver 2 . Therefore, the servo driver 2 can detect replacement of the motor 3 by acquiring the model name and serial number of the motor body 30 and the serial number of the encoder 31 from the storage unit 313 . However, if the suppliers of the servo driver 2 and the motor 3 are different (for example, if the suppliers of the servo driver 2 and the encoder 31 are different), the supplier of the servo driver 2 cannot grasp the configuration of the storage unit 313. , the supplier of the servo driver 2 cannot set the configuration of the storage unit 313 in the servo driver 2 . Therefore, the servo driver 2 cannot acquire the model name and serial number of the motor 3 and the serial number of the encoder 31 from the storage unit 313 of the newly connected motor 3, and cannot detect the replacement of the motor 3. Therefore, in the present embodiment, in order to solve such problems, the servo driver 2 includes functional units described below.

FIG. 4 is a diagram showing a schematic configuration of functional units of the servo driver 2. As shown in FIG. The servo driver 2 can be regarded as a computer having an arithmetic device, a storage device, and the like. The functional units shown in FIG. 4 are implemented by executing a predetermined program or the like in the servo driver 2 . The servo driver 2 has a communication section 21, a servo control section 22, a calculation section 23, a detection section 24, and a storage section 25, but may have functional sections other than these.

The communication unit 21 is a function that controls communication with the outside via the communication cable 11 . For example, the communication part 21 functions as an interface for communication with PLC1. Furthermore, the communication unit 21 also functions as an interface for communication with the encoder 31 via the encoder cable 41 .

The servo control unit 22 is a functional unit for servo-controlling the motor 3 based on commands from the PLC 1. Specifically, it performs feedback control using a position controller, a speed controller, a current controller, and the like. It is a functional part. For the position controller, speed controller, current controller, etc., control parameters such as speed gain are appropriately set so that servo control of the motor 3 to be controlled is preferably performed.

The calculation unit 23 acquires data stored in the storage unit 313 of the encoder 31, for example, when the servo driver 2 is energized. Here, the calculation unit 23 does not need to interpret the meaning of the acquired data. Therefore, the detection unit 24 may acquire the data stored in the storage unit 313 simply as a bit string (a block of data). Then, the calculation unit 23 inputs the data acquired from the storage unit 313 to the hash function to perform arithmetic processing for calculating a hash value.

Here, hash functions of various algorithms can be used as the hash functions used by the calculator 23 . Examples of hash function algorithms used by the detection unit 24 include SHA-1, SHA-256, and SHA-512.

The detection unit 24 is a functional unit that detects replacement of the motor 3 . The detection unit 24 causes the storage unit 25 to store the calculated hash value calculated by the calculation unit 23 . Then, the detection unit 24 compares the hash value calculated when the servo driver 2 is energized with the hash value already stored in the storage unit 25, and if these hash values are different, it means that the motor 3 has been replaced. detect.

The storage unit 25 is a functional unit that stores various data related to processing performed by the servo driver 2, such as data used for servo control of the motor 3 and hash values calculated by the calculation unit 23.

Next, a detection flow for detecting replacement of the motor 3 by the servo driver 2 will be described. FIG. 5 is a diagram showing a processing flow for detecting replacement of the motor 3 by the servo driver 2. As shown in FIG. The processing flow shown in FIG. 5 is executed, for example, when the servo driver 2 is energized (at startup). A processing flow for detecting replacement of the motor 3 by the detection unit 24 will be described below with reference to FIG.

In S<b>1 , the calculation unit 23 acquires all data stored in the storage unit 313 of the encoder 31 . In S2, the calculator 23 inputs all the data acquired in S1 to a hash function to calculate a hash value.

In S<b>3 , the detection unit 24 determines whether or not there is a stored hash value in the storage unit 25 . If there is a stored hash value (YES in S3), the process proceeds to S4. If there is no stored hash value (NO in S3), the process proceeds to S6.

In S<b>4 , the detection unit 24 compares the hash value calculated by the calculation unit 23 in S<b>2 with the hash value already stored in the storage unit 25 . If these hash values match (YES in S4), it is determined that the motor 3 has not been replaced, so the process proceeds to S7. If these hash values are different (NO in S4), the process proceeds to S5.

In S<b>5 , the detection unit 24 detects replacement of the motor 3 . The detection unit 24 that has detected replacement of the motor 3 outputs, for example, an alarm and does not start driving the motor 3 . The output of the alarm may be, for example, output of a buzzer sound. Moreover, the output of an alarm may be realized by transmitting a message to a host device such as the PLC 1 or the like. Since the process of S7 is not executed in the process flow reaching S5, the process of starting to drive the motor 3 is prohibited.

In S<b>6 , the calculation unit 23 stores the hash value calculated in S<b>2 in the storage unit 25 . If there is already a stored hash value, the calculation unit 23 deletes the stored hash value and then stores the hash value calculated in S2 when the servo driver 2 is energized this time. The stored hash value is used, for example, for determination in S4 when the servo driver 2 is energized next time. In S<b>7 , the servo control section 22 starts driving the motor 3 .

In the embodiment described above, the servo driver 2 calculates hash values for all data stored in the storage unit 313 of the encoder 31, and detects replacement of the motor 3 by comparing the calculated hash values. Therefore, the servo driver 2 can detect the replacement of the motor 3 even if it is unknown what kind of data is stored in which area of the storage unit 313 .

The servo driver 2 employs hash values for comparison of all data stored in the storage unit 313 of the encoder 31 . The hash value is fixed-length data according to the algorithm of the hash function. That is, even if the amount of data stored in the storage unit 313 is large, the size of hash values does not increase. Therefore, according to the present embodiment, it is possible to reduce the capacity of the storage unit 25 used for storing hash values. Further, by using the hash value when comparing the data stored in the storage unit 313, the calculation load of the servo driver 2 can be reduced compared to comparing the data stored in the storage unit 313 as they are.

<First modification>
In the embodiment described above, preset data was saved in the storage unit 313 of the encoder 31 . In the first modification, a case will be described in which variable data whose values fluctuate, such as measurement data measured by various sensors such as a temperature sensor, is also stored in the storage unit 313 .

FIG. 6 is a second diagram showing an example of data stored in the storage unit 313 of the encoder 31. As shown in FIG. In the example of FIG. 6 , in addition to the data shown in FIG. 3 , measurement data measured by various sensors connected to the encoder 31 are also stored in the storage unit 313 . Therefore, when the detection unit 24 acquires the data in the entire area of the storage unit 313 and calculates the hash value, the hash value may differ even if the motor 3 is not replaced. Therefore, the detection unit 24 may erroneously detect replacement of the motor 3 .

Therefore, the calculation unit 23 acquires data saved in an area other than the area in which the variable data is saved, among the data saved in the storage unit 313, and calculates the hash value thereof. For example, the calculation unit 23 may specify, in a command to access the storage unit 313, to acquire all data except for the area where variable data is stored.

FIG. 7 is a diagram showing a detection flow for detecting replacement of the motor 3 by the servo driver 2 in the first modified example. The detection flow shown in FIG. 7 differs from the detection flow shown in FIG. 5 in that S1a is executed instead of S1.

In S1a, the calculation unit 23 instructs the command to acquire data from the storage unit 313 to acquire all data other than the area where the variable data is stored. 5, the calculation unit 23 acquires the data stored in the entire area of the storage unit 313, while in S1a of FIG. Get data stored in 313.

In the first modified example, the data stored in the storage unit 313 is acquired by excluding the area where the variable data is stored, and the hash value of the acquired data is calculated. Therefore, even if the value of the variable data stored in the storage unit 313 fluctuates, the hash value does not fluctuate unless the motor 3 is replaced. Therefore, according to the first modification, the detection unit 24 can detect replacement of the motor 3 even when the variable data is stored in the storage unit 313 .

<Second modification>
In the embodiment described above, the hash value of data acquired from the storage unit 313 is calculated using one hash function. In the second modification, an example of calculating hash values of data acquired from the storage unit 313 using hash functions of two different algorithms will be described.

FIG. 8 is a diagram showing a detection flow for detecting replacement of the motor 3 by the servo driver 2 in the second modification. The detection flow shown in FIG. 8 differs from the detection flow shown in FIG. 5 in that S2a is executed instead of S2, S4a is executed instead of S4, and S6a is executed instead of S6.

In S2a, the calculator 23 uses two hash functions with different algorithms to calculate the hash value of the data acquired in S1. The calculation unit 23 calculates the hash value of the data acquired in S1, for example, using the SHA-1 hash function. Further, the calculation unit 23 calculates a hash value of the data acquired in S1 using the SHA-256 hash function.

In S4a, the detection unit 24 compares the two hash values calculated in S2a with the two hash values stored in S6. That is, the detection unit 24 compares the hash value calculated by SHA-1 and stored in S6 with the hash value newly calculated by SHA-1 in S2a. Further, the detection unit 24 compares the hash value calculated by SHA-256 and stored in S6 with the hash value newly calculated by SHA-256 in S2a. As a result of this comparison, if at least one of the hash value calculated by SHA-1 and the hash value calculated by SHA-256 does not match (NO in S4a), the process proceeds to S5. If both hash values match (YES in S4a), the process proceeds to S7.

In S6a, the calculation unit 23 stores the two hash values calculated in S2a in the storage unit 25. FIG. If there is already a stored hash value, the calculation unit 23 deletes the stored hash value and then stores the two hash values calculated in S2a when the servo driver 2 is energized this time. conduct. For example, the calculation unit 23 may store the two hash values in the storage unit 25 in association with the calculated algorithm.

The hash function may calculate the same hash value despite different input data (occurrence of collision). In the second modification, each hash value is calculated using hash functions of two different algorithms for the data acquired from the storage unit 313, and if the hash values calculated by at least one of the algorithms do not match in S4a, , the replacement of the motor 3 is detected. It is considered that the probability of occurrence of collision between hash functions of two different algorithms for the same input data is extremely low. Therefore, according to the second modification, it is possible to improve the accuracy of detecting replacement of the motor 3 .

The embodiments and modifications described above can be combined.

<Appendix 1>
A servo driver (2) for controlling a servo motor (3) including an encoder (31) and a motor body (30),
a servo control unit (22) for servo-controlling the servo motor (3);
Data in a non-volatile memory (313) provided in the encoder (31), which is accessible from the servo driver (2) when the servo driver (2) is energized, is stored as a set of predetermined data. a calculation unit (23) that performs arithmetic processing for obtaining data and inputting the obtained predetermined data to a hash function to calculate a hash value;
a storage unit (25) that stores the hash value calculated by the calculation unit (23);
When the servo driver (2) is next energized, the arithmetic processing by the calculation unit (23) is performed on the nonvolatile memory (313) of the predetermined encoder (31) accessible from the servo driver (2). a detection unit (24) for detecting replacement of the servo motor (3) when a predetermined hash value obtained by performing the above is different from the hash value stored in the storage unit (25);
a servo driver (2).

<Appendix 2>
a servo motor (3) including an encoder (31) and a motor body (30);
A servo system (100) comprising a servo driver (2) for controlling the servo motor (3),
The servo driver (2)
a servo control unit (22) for servo-controlling the servo motor (3);
A memory (313) provided in the encoder (31), which is a non-volatile memory (313) accessible from the servo driver (2) when the servo driver (2) is energized. a calculation unit (23) that acquires data and performs arithmetic processing to calculate a hash value by inputting the acquired predetermined data into a hash function; and a storage unit that stores the hash value calculated by the calculation unit (23). (25) and
When the servo driver (2) is next energized, the calculation unit (
23) is different from the hash value stored in the storage unit (25), a detection unit (24) for detecting replacement of the servo motor (3). and including
A servo system (100).

1 PLC
2 Servo driver 3 Motor 8 Work 21 Communication unit 22 Servo control unit 23 Calculation unit 24 Detection unit 25 Storage unit 30 Motor body 31 Encoder 311 Signal generation unit 312 Communication unit 313 Storage unit 32 Output shaft 41 Encoder cable 51 Coupling 52 Screw shaft 53 Precision stage 53
100 Servo system

Claims (12)

A servo driver for controlling a servo motor including an encoder and a motor body,
a servo control unit that servo-controls the servo motor;
Data in a non-volatile memory provided in the encoder and accessible from the servo driver when the servo driver is energized is acquired as a block of predetermined data, and the acquired predetermined data is input to a hash function. a calculation unit that performs arithmetic processing to calculate a hash value by
a storage unit that stores the hash value calculated by the calculation unit;
When the servo driver is energized next time, the storage unit stores a predetermined hash value obtained by performing the arithmetic processing by the calculation unit on a nonvolatile memory of a predetermined encoder accessible from the servo driver. a detection unit that detects replacement of the servo motor when the hash value differs from the hash value to be used;
a servo driver. The storage unit stores the hash value calculated by the calculation unit when the most recent servo driver is energized.
The servo driver according to claim 1. The calculation unit acquires all data stored in the nonvolatile memory of the encoder as the predetermined data.
The servo driver according to claim 1 or 2. The calculation unit obtains, as the predetermined data, data excluding variable data that is accessible to the servo driver and whose value fluctuates, from the data stored in the nonvolatile memory of the encoder.
The servo driver according to claim 1 or 2. The calculation unit
calculating a hash value of the predetermined data for each of a first hash function of a first algorithm and a second hash function of a second algorithm in the arithmetic processing;
The detection unit is
comparing a hash value calculated by the first hash function stored in the storage unit with a hash value obtained by using the first hash function in the arithmetic processing when the next servo driver is energized;
comparing the hash value calculated by the second hash function stored in the storage unit and the hash value obtained by using the second hash function in the arithmetic processing when the next servo driver is energized;
Detecting the replacement of the servo motor when at least one of the hash value calculated by the first hash function and the hash value calculated by the second hash function is different.
A servo driver according to any one of claims 1 to 4. When the detection unit detects replacement of the servo motor when the servo driver is energized, the servo control unit prohibits control of the servo motor connected to the servo driver at that time.
A servo driver according to any one of claims 1 to 5. a servo motor including an encoder and a motor body;
A servo system comprising a servo driver that controls the servo motor,
The servo driver
a servo control unit that servo-controls the servo motor;
Data in a non-volatile memory provided in the encoder and accessible from the servo driver when the servo driver is energized is acquired as a block of predetermined data, and the acquired predetermined data is input to a hash function. a calculation unit that performs arithmetic processing to calculate a hash value by calculating a hash value; a storage unit that stores the hash value calculated by the calculation unit;
When the servo driver is energized next time, the storage unit stores a predetermined hash value obtained by performing the arithmetic processing by the calculation unit on a nonvolatile memory of a predetermined encoder accessible from the servo driver. a detection unit that detects replacement of the servo motor if the hash value differs from the hash value that
servo system. The storage unit stores the hash value calculated by the calculation unit when the most recent servo driver is energized.
A servo system according to claim 7. The calculation unit acquires all data stored in the nonvolatile memory of the encoder as the predetermined data.
9. Servo system according to claim 7 or 8. The calculation unit obtains, as the predetermined data, data excluding variable data that is accessible to the servo driver and whose value fluctuates, from the data stored in the nonvolatile memory of the encoder.
9. Servo system according to claim 7 or 8. The calculation unit
calculating a hash value of the predetermined data for each of a first hash function of a first algorithm and a second hash function of a second algorithm in the arithmetic processing;
comparing a hash value calculated by the first hash function stored in the storage unit with a hash value obtained by using the first hash function in the arithmetic processing when the next servo driver is energized;
comparing the hash value calculated by the second hash function stored in the storage unit and the hash value obtained by using the second hash function in the arithmetic processing when the next servo driver is energized;
Detecting the replacement of the servo motor when at least one of the hash value calculated by the first hash function and the hash value calculated by the second hash function is different.
Servo system according to any one of claims 7 to 10. When the detection unit detects replacement of the servo motor when the servo driver is energized, the servo control unit prohibits control of the servo motor connected to the servo driver at that time.
Servo system according to any one of claims 7 to 11.

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